From 82df4c64ffa2f0dd45e7ae694903615358f121a6 Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Fri, 2 Nov 2018 19:19:39 -0700 Subject: [PATCH] Add descriptor expansion cache --- src/script/descriptor.cpp | 78 +++++++++++++++++++++++------------ src/script/descriptor.h | 12 +++++- src/test/descriptor_tests.cpp | 15 +++++-- 3 files changed, 75 insertions(+), 30 deletions(-) diff --git a/src/script/descriptor.cpp b/src/script/descriptor.cpp index adb5d20ed..a702be5b7 100644 --- a/src/script/descriptor.cpp +++ b/src/script/descriptor.cpp @@ -40,8 +40,8 @@ struct PubkeyProvider { virtual ~PubkeyProvider() = default; - /** Derive a public key. */ - virtual bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key, KeyOriginInfo& info) const = 0; + /** Derive a public key. If key==nullptr, only info is desired. */ + virtual bool GetPubKey(int pos, const SigningProvider& arg, CPubKey* key, KeyOriginInfo& info) const = 0; /** Whether this represent multiple public keys at different positions. */ virtual bool IsRange() const = 0; @@ -68,7 +68,7 @@ class OriginPubkeyProvider final : public PubkeyProvider public: OriginPubkeyProvider(KeyOriginInfo info, std::unique_ptr provider) : m_origin(std::move(info)), m_provider(std::move(provider)) {} - bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key, KeyOriginInfo& info) const override + bool GetPubKey(int pos, const SigningProvider& arg, CPubKey* key, KeyOriginInfo& info) const override { if (!m_provider->GetPubKey(pos, arg, key, info)) return false; std::copy(std::begin(m_origin.fingerprint), std::end(m_origin.fingerprint), info.fingerprint); @@ -94,9 +94,9 @@ class ConstPubkeyProvider final : public PubkeyProvider public: ConstPubkeyProvider(const CPubKey& pubkey) : m_pubkey(pubkey) {} - bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key, KeyOriginInfo& info) const override + bool GetPubKey(int pos, const SigningProvider& arg, CPubKey* key, KeyOriginInfo& info) const override { - key = m_pubkey; + if (key) *key = m_pubkey; info.path.clear(); CKeyID keyid = m_pubkey.GetID(); std::copy(keyid.begin(), keyid.begin() + sizeof(info.fingerprint), info.fingerprint); @@ -152,26 +152,28 @@ public: BIP32PubkeyProvider(const CExtPubKey& extkey, KeyPath path, DeriveType derive) : m_extkey(extkey), m_path(std::move(path)), m_derive(derive) {} bool IsRange() const override { return m_derive != DeriveType::NO; } size_t GetSize() const override { return 33; } - bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key, KeyOriginInfo& info) const override + bool GetPubKey(int pos, const SigningProvider& arg, CPubKey* key, KeyOriginInfo& info) const override { - if (IsHardened()) { - CExtKey extkey; - if (!GetExtKey(arg, extkey)) return false; - for (auto entry : m_path) { - extkey.Derive(extkey, entry); + if (key) { + if (IsHardened()) { + CExtKey extkey; + if (!GetExtKey(arg, extkey)) return false; + for (auto entry : m_path) { + extkey.Derive(extkey, entry); + } + if (m_derive == DeriveType::UNHARDENED) extkey.Derive(extkey, pos); + if (m_derive == DeriveType::HARDENED) extkey.Derive(extkey, pos | 0x80000000UL); + *key = extkey.Neuter().pubkey; + } else { + // TODO: optimize by caching + CExtPubKey extkey = m_extkey; + for (auto entry : m_path) { + extkey.Derive(extkey, entry); + } + if (m_derive == DeriveType::UNHARDENED) extkey.Derive(extkey, pos); + assert(m_derive != DeriveType::HARDENED); + *key = extkey.pubkey; } - if (m_derive == DeriveType::UNHARDENED) extkey.Derive(extkey, pos); - if (m_derive == DeriveType::HARDENED) extkey.Derive(extkey, pos | 0x80000000UL); - key = extkey.Neuter().pubkey; - } else { - // TODO: optimize by caching - CExtPubKey extkey = m_extkey; - for (auto entry : m_path) { - extkey.Derive(extkey, entry); - } - if (m_derive == DeriveType::UNHARDENED) extkey.Derive(extkey, pos); - assert(m_derive != DeriveType::HARDENED); - key = extkey.pubkey; } CKeyID keyid = m_extkey.pubkey.GetID(); std::copy(keyid.begin(), keyid.begin() + sizeof(info.fingerprint), info.fingerprint); @@ -285,7 +287,7 @@ public: bool ToPrivateString(const SigningProvider& arg, std::string& out) const override final { return ToStringHelper(&arg, out, true); } - bool Expand(int pos, const SigningProvider& arg, std::vector& output_scripts, FlatSigningProvider& out) const final + bool ExpandHelper(int pos, const SigningProvider& arg, Span* cache_read, std::vector& output_scripts, FlatSigningProvider& out, std::vector* cache_write) const { std::vector> entries; entries.reserve(m_pubkey_args.size()); @@ -293,12 +295,25 @@ public: // Construct temporary data in `entries` and `subscripts`, to avoid producing output in case of failure. for (const auto& p : m_pubkey_args) { entries.emplace_back(); - if (!p->GetPubKey(pos, arg, entries.back().first, entries.back().second)) return false; + if (!p->GetPubKey(pos, arg, cache_read ? nullptr : &entries.back().first, entries.back().second)) return false; + if (cache_read) { + // Cached expanded public key exists, use it. + if (cache_read->size() == 0) return false; + bool compressed = ((*cache_read)[0] == 0x02 || (*cache_read)[0] == 0x03) && cache_read->size() >= 33; + bool uncompressed = ((*cache_read)[0] == 0x04) && cache_read->size() >= 65; + if (!(compressed || uncompressed)) return false; + CPubKey pubkey(cache_read->begin(), cache_read->begin() + (compressed ? 33 : 65)); + entries.back().first = pubkey; + *cache_read = cache_read->subspan(compressed ? 33 : 65); + } + if (cache_write) { + cache_write->insert(cache_write->end(), entries.back().first.begin(), entries.back().first.end()); + } } std::vector subscripts; if (m_script_arg) { FlatSigningProvider subprovider; - if (!m_script_arg->Expand(pos, arg, subscripts, subprovider)) return false; + if (!m_script_arg->ExpandHelper(pos, arg, cache_read, subscripts, subprovider, cache_write)) return false; out = Merge(out, subprovider); } @@ -322,6 +337,17 @@ public: } return true; } + + bool Expand(int pos, const SigningProvider& provider, std::vector& output_scripts, FlatSigningProvider& out, std::vector* cache = nullptr) const final + { + return ExpandHelper(pos, provider, nullptr, output_scripts, out, cache); + } + + bool ExpandFromCache(int pos, const std::vector& cache, std::vector& output_scripts, FlatSigningProvider& out) const final + { + Span span = MakeSpan(cache); + return ExpandHelper(pos, DUMMY_SIGNING_PROVIDER, &span, output_scripts, out, nullptr) && span.size() == 0; + } }; /** Construct a vector with one element, which is moved into it. */ diff --git a/src/script/descriptor.h b/src/script/descriptor.h index 0111972f8..44f0efca0 100644 --- a/src/script/descriptor.h +++ b/src/script/descriptor.h @@ -48,8 +48,18 @@ struct Descriptor { * provider: the provider to query for private keys in case of hardened derivation. * output_script: the expanded scriptPubKeys will be put here. * out: scripts and public keys necessary for solving the expanded scriptPubKeys will be put here (may be equal to provider). + * cache: vector which will be overwritten with cache data necessary to-evaluate the descriptor at this point without access to private keys. */ - virtual bool Expand(int pos, const SigningProvider& provider, std::vector& output_scripts, FlatSigningProvider& out) const = 0; + virtual bool Expand(int pos, const SigningProvider& provider, std::vector& output_scripts, FlatSigningProvider& out, std::vector* cache = nullptr) const = 0; + + /** Expand a descriptor at a specified position using cached expansion data. + * + * pos: the position at which to expand the descriptor. If IsRange() is false, this is ignored. + * cache: vector from which cached expansion data will be read. + * output_script: the expanded scriptPubKeys will be put here. + * out: scripts and public keys necessary for solving the expanded scriptPubKeys will be put here (may be equal to provider). + */ + virtual bool ExpandFromCache(int pos, const std::vector& cache, std::vector& output_scripts, FlatSigningProvider& out) const = 0; }; /** Parse a descriptor string. Included private keys are put in out. Returns nullptr if parsing fails. */ diff --git a/src/test/descriptor_tests.cpp b/src/test/descriptor_tests.cpp index 0e98f5a82..1a35b5ea7 100644 --- a/src/test/descriptor_tests.cpp +++ b/src/test/descriptor_tests.cpp @@ -88,9 +88,18 @@ void Check(const std::string& prv, const std::string& pub, int flags, const std: const auto& ref = scripts[(flags & RANGE) ? i : 0]; for (int t = 0; t < 2; ++t) { const FlatSigningProvider& key_provider = (flags & HARDENED) ? keys_priv : keys_pub; - FlatSigningProvider script_provider; - std::vector spks; - BOOST_CHECK((t ? parse_priv : parse_pub)->Expand(i, key_provider, spks, script_provider)); + FlatSigningProvider script_provider, script_provider_cached; + std::vector spks, spks_cached; + std::vector cache; + BOOST_CHECK((t ? parse_priv : parse_pub)->Expand(i, key_provider, spks, script_provider, &cache)); + + // Try to expand again using cached data, and compare. + BOOST_CHECK(parse_pub->ExpandFromCache(i, cache, spks_cached, script_provider_cached)); + BOOST_CHECK(spks == spks_cached); + BOOST_CHECK(script_provider.pubkeys == script_provider_cached.pubkeys); + BOOST_CHECK(script_provider.scripts == script_provider_cached.scripts); + BOOST_CHECK(script_provider.origins == script_provider_cached.origins); + BOOST_CHECK_EQUAL(spks.size(), ref.size()); for (size_t n = 0; n < spks.size(); ++n) { BOOST_CHECK_EQUAL(ref[n], HexStr(spks[n].begin(), spks[n].end()));